package com.wuzao;

import cn.hutool.core.util.ObjUtil;

import java.util.HashMap;

public class Main {
    public static void main(String[] args) {
        System.out.println("Hello world!");

        Object obj = null;
        System.out.println(ObjUtil.isNull(obj));

        HashMap<String, String> hashMap = new HashMap<>();
        hashMap.put("1", "1");
        System.out.println(hashMap);
    }
}